Project Leadership Team

Objective

In this project, high level computational chemistry methods will be used to investigate thermodynamic and kinetic
properties of a number of gas phase Hg reactions in atmospheric chemistry. The list of reactions to be studied include
binary gas phase reactions of Hg compounds with the free radicals Cl, ClO, Br, BrO, O3, NO3,
NO2, NO, OH, HO2, CH3O2, and CH3O. The list, while not inclusive,
contains many of the gas phase reactions that are thought to be important in atmospheric chemistry for predicting the
oxidation rates of Hg0 to HgII compounds. The thermodynamic data developed in this work will be used to identify reactions
that may be contributing to speciation of mercury in the atmosphere. Rate constants for a number of the more promising gas
phase chemical reactions will be estimated using a semi-empirical approach to unimolecular decomposition, variational
transition state theory, and Rice-Ramsperger-Kassel-Marcus (RRKM) theory, as appropriate. This information will be used to
estimate the atmospheric lifetimes and fates of Hg compounds.

Using quantum mechanical computational techniques, we can safely and accurately calculate the thermodynamic properties of
reactions involving mercury. This information will help us examine the relevant reactions which determine the fate of mercury
in the atmosphere. Such data is necessary in order to a) design effective remediation processes; b) predict kinetic properties
of relevant reactions (as determined from step a); and c) understand how the atmospheric mercury ends up contaminating not just
the land and water, but the food chain as well. Computational analyses are well suited to the analysis of the subsequent
bioactivity of mercury.

The calculated thermo-chemical, kinetic, and aerosol data will provide important input into the models used in simulations
needed for the prediction of the environmental impact of mercury. This project will bring together a diverse group of
computational and experimental scientists to investigate the fate of mercury in the atmosphere, land and waterways. The outcome of
the project will have a profound impact on the economic development of the coastal plains of Eastern North Carolina. Hopefully, the
results of this study will contribute to the development of new technologies to prevent mercury from poisoning the coastal plains
and will expedite the removal of existing contaminates.

Task 1: Atmospheric Thermo-Chemistry

Construction of numerical and analytic all-electron basis sets for Mercury

Identify important gas phase reactions

Update literature search

Perform geometry optimizations of all reactants and products

Perform frequency calculations on all possible reactants and products

Build database of results

Calculate thermodynamic data and equilibrium constants of all reactions considered